Priorities for soil research and sustainable management in Madagascar

Razafimbelo, Tantely; Albrecht, Alain; Becquer, Thierry; Bernard, Lætitia; Chevallier, Tiphaine; Erktan, Amandine; Chapuis‐Lardy, Lydie; Trap, Jean; Andriamananjara, Andry; Rabenarivo, Michel; Rafolisy, Tovonarivo; Rakotoson, Tovohery; Ramifehiarivo, Nandrianina; Razafindrakoto, Malatiana; Blanchart, Éric

doi:10.1016/j.geodrs.2022.e00518

Cited by 2 publications

(2 citation statements)

References 10 publications

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“…Whereas Madagascar’s highlands were undoubtedly transformed by human activities—as is true of almost every corner of the planet ( 181 )—erosion and gully formation also occur independent of human intervention. Reliable interpretations therefore require careful observations of the landscape, considering all possible forcing factors, and there is a pressing need to understand how human and background forcing factors intersect in driving landscape change in Madagascar, as stressed recently by Razafimbelo et al ( 182 ). Policy needs to be calibrated, not simply to marked and apparently obvious processes (such as lavaka erosion) but also to the “slow variables” that underpin the system (including seismicity and tectonic uplift).…”

Section: Discussionmentioning

confidence: 99%

Gullying and landscape evolution: Lavaka in Lac Alaotra, Madagascar shed light on rates of change and non-anthropogenic controls

Cox,

Phillips,

Rakotondrazafy

2024

Sci. Adv.

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Gully evolution remains poorly understood, largely because multidecadal analysis is lacking. Large gullies (called lavaka) that pepper Madagascar’s highlands are generally attributed to human impact; but longitudinal data are few, and anthropogenic causation is inferred not verified. We focus on Lac Alaotra, Madagascar’s largest lake and wetland, its major rice-growing region, and an ecological hotspot surrounded by fault-controlled steep hills with abundant lavaka. Analysis of historical aerial photographs and recent orthoimagery reveals that the proportion of highly active lavaka has decreased since mid-20th century. At the same time, human population, farming intensity, and livestock density have increased exponentially. This suggests that background factors, including seismicity, are primary drivers of lavaka formation. Although human activities may contribute to erosion overall, land management policies that overemphasize human causation of gullying and neglect background forcing factors (in Madagascar and elsewhere) are unlikely to be effective in erosion mitigation.

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Section: Discussionmentioning

confidence: 99%

Gullying and landscape evolution: Lavaka in Lac Alaotra, Madagascar shed light on rates of change and non-anthropogenic controls

Cox,

Phillips,

Rakotondrazafy

2024

Sci. Adv.

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“…The majority of studies emphasise lavaka as indicators of environmental degradation in a landscape out of geomorphic equilibrium (e.g., Bakoariniaina et al, 2006; Brosens, Broothaerts, et al, 2022; Brosens, Campforts, et al, 2022; Gade, 1996), and little attention has been paid to ways in which Malagasy farmers use lavaka and find benefit from them. However, lavaka offer opportunities to many farmers—particularly those with tanety (i.e., non‐terraced cultivation on hillsides)—who struggle with the well‐documented lack of nutrients in Madagascar's highland soils (Raminoarison et al, 2020; Rasoamampionona et al, 2008; Razafimbelo et al, 2022). Many tanety farmers have realised that lavaka furnish an alternative set of growing conditions that can be used to advantage and sustainably.…”

Section: Lavaka and Agriculturementioning

confidence: 99%

Lavaka (erosional gullies) provide productive patch environments for flora and farming in Madagascar's grassy highlands

Cox,

Carrère,

Rakotondrazafy

et al. 2023

Plants People Planet

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Societal Impact StatementLavaka, large gullies in Madagascar, can cause problems for farmers and for infrastructure, but these features also have beneficial aspects that have generally been overlooked. They provide plant refugia, and commonly host species that would otherwise not thrive on the grassy uplands. Farmers sometimes make use of lavaka to plant crops that require more protection or soil moisture. Colonial narratives blame lavaka erosion on poor land management but ignore their pre‐human‐settlement existence on the landscape and the ecological functions they serve. The knowledge and wisdom of Malagasy farmers are key to better understanding the complex roles that lavaka plays in the landscape.SummaryThis paper combines a review of lavaka—erosional gullies in Madagascar's grass‐covered highlands—with new observations of their importance as ecological patch environments for a wide range of plants not seen elsewhere within the grassy biome. Lavaka play a role as a natural refugia for flora that would otherwise not thrive on the exposed and infertile hillslopes, and local farmers exploit their topography and sediment deposits to grow a variety of crops. We provide a classification scheme for lavaka based on the extent to which they have been colonised by vegetation. Our analysis is based on observations made over many field seasons in the highlands as well as interviews with Malagasy farmers living with lavaka on their land. We emphasise the importance of local knowledge and environmental wisdom in the analysis of landscape evolution, and we conclude that lavaka, while certainly an erosional problem in many places, can nonetheless provide valuable ecosystem services and agricultural opportunities that should not be overlooked.

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Priorities for soil research and sustainable management in Madagascar

Cited by 2 publications

References 10 publications

Gullying and landscape evolution: Lavaka in Lac Alaotra, Madagascar shed light on rates of change and non-anthropogenic controls

Gullying and landscape evolution: Lavaka in Lac Alaotra, Madagascar shed light on rates of change and non-anthropogenic controls

Lavaka (erosional gullies) provide productive patch environments for flora and farming in Madagascar's grassy highlands

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